System and method for improved gnss sensitivity via combining acquisition and track correlation hypotheses

ABSTRACT

An apparatus, a method, a method of manufacturing an apparatus, and a method of constructing an integrated circuit are provided. The apparatus includes a memory and a processor configured to conduct acquisition of K values with N peaks, where K and N are integers; store the K values in the memory; select J of the N peaks and include the J peaks in track, where J is an integer less than or equal to N; combine acquisition and track non-coherent summations (NCSs) of coherent correlations in a metric; and form a measurement unless the metric indicates that the measurement should be abandoned.

PRIORITY

This application claims priority under 35 U.S.C. § 119(e) to a U.S.Provisional Patent Application filed on Oct. 25, 2017 in the UnitedStates Patent and Trademark Office and assigned Ser. No. 62/576,781, theentire contents of which are incorporated herein by reference.

FIELD

The present disclosure relates generally to a Global NavigationSatellite System (GNSS) receiver, and more particularly, to a system anda method for improved GNSS sensitivity, speed, and quality of availablemeasurements.

BACKGROUND

Modern GNSS receiver performance is aided by injecting fine time andfrequency into the receiver to narrow code phase and carrier frequencyuncertainty in the receiver. Such aiding information can reduce thenumber of signal hypotheses tested from a range of tens of thousands tohundreds. The aiding information has been built into various standardssuch that modern Code Division Multiple Access (CDMA) and Long-TermEvolution (LTE) networks may supply a receiver with accurate time (e.g.±10 μsecs), and accurate frequency (e.g. ±0.1 ppm, approximately ±160 Hzfor GNSS). This is done largely by a call processor (CP) measuring alocal temperature compensated crystal oscillator (TCXO) against a clockof a base station of a cell.

A typical receiver has an acquisition phase where a search of a numberof code phase and carrier frequency hypotheses is performed and the bestenergy is selected for track. Track is a mode that assumes a presence ofsignal energy within a narrow operating range (e.g., within ±1 chip codephase and within ±10 Hz of carrier frequency). To track indicates tokeep an incoming signal's energy and local replica's aligned such thatas the incoming signal's parameters change the local replica is able tofollow. In general, track is done by measuring a difference between twosignals and feeding back corrections to a local replica to maintainalignment. In the case of fine aiding availability, multiple hypotheses(e.g. several hundred) may be integrated for an integration time (e.g. 5seconds) and the hypotheses with the highest energy put into a trackphase (indicating that code and carrier tracking loops are closed). Forexample, integration is performed on each hypothesis during acquisitionwith 20 milliseconds of coherent integration followed by non-coherentaccumulation of the coherent summation across 5 seconds. Typically, whenan acquisition hypothesis is put into track, the effective integrationis restarted.

SUMMARY

According to one embodiment, an apparatus includes a memory; and aprocessor configured to conduct acquisition of K values with N peaks,where K and N are integers; store the K values in the memory; select Jof the N peaks and include the J peaks in track, where J is an integerless than or equal to N; combine acquisition and track non-coherentsummations (NCSs) of coherent correlations in a metric; and form ameasurement unless the metric indicates that the measurement should beabandoned.

According to one embodiment, a method includes performing, by aprocessor, acquisition of K values with N peaks, where K and N areintegers; storing, in a memory, the K values; selecting J of the N peaksand including the J peaks in track, where J is an integer less than orequal to N; combining acquisition and track NCSs of coherentcorrelations in a metric; and forming a measurement unless the metricindicates that the measurement should be abandoned.

According to one embodiment, a method of manufacturing an apparatusincludes forming the apparatus on a wafer or a package with at least oneother apparatus, wherein the apparatus includes a memory and a processorconfigured to conduct acquisition of K values with N peaks, where K andN are integers, store the K values in the memory, select J of the Npeaks and include the J peaks in track, where J is an integer less thanor equal to N, combine acquisition and track NCSs of coherentcorrelations in a metric; and form a measurement unless the metricindicates that the measurement should be abandoned, and testing theapparatus using one or more electrical to optical converters, one ormore optical splitters that split an optical signal into two or moreoptical signals, and one or more optical to electrical converters.

According to one embodiment, a method of constructing an integratedcircuit includes generating a mask layout for a set of features for alayer of the integrated circuit, wherein the mask layout includesstandard cell library macros for one or more circuit features thatinclude an apparatus that includes a memory and a processor configuredto conduct acquisition of K values with N peaks, where K and N areintegers, store the K values in the memory, select J of the N peaks andinclude the J peaks in track, where J is an integer less than or equalto N, combine acquisition and track NCSs of coherent correlations in ametric; and form a measurement unless the metric indicates that themeasurement should be abandoned; disregarding relative positions of themacros for compliance to layout design rules during the generation ofthe mask layout; checking the relative positions of the macros forcompliance to layout design rules after generating the mask layout; upondetection of noncompliance with the layout design rules by any of themacros, modifying the mask layout by modifying each of the noncompliantmacros to comply with the layout design rules; generating a maskaccording to the modified mask layout with the set of features for thelayer of the integrated circuit; and manufacturing the integratedcircuit layer according to the mask.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the present disclosure will be more apparent from thefollowing detailed description, taken in conjunction with theaccompanying drawings, in which:

FIG. 1 is a block diagram of a GNSS receiver, according to oneembodiment;

FIG. 2 is an illustration of an acquisition search space, according toone embodiment;

FIG. 3 is an illustration of an acquisition peak and adjacentcorrelators in code phase and carrier frequency domains, according toone embodiment;

FIG. 4 is a chart of a waveform of acquisition/track frequency bins,according to one embodiment;

FIG. 5 is an illustration of an on-frequency bin correlator usage mode,according to one embodiment;

FIG. 6 is an illustration of non-coherent summation (NCS) propagation,according to one embodiment;

FIG. 7 is a flowchart of a method of NCS propagation, according to oneembodiment;

FIG. 8 is an illustration of an acquisition phase and a track phasetimeline, according to one embodiment;

FIG. 9 is a flowchart of a method of acquisition and track processes,according to one embodiment;

FIG. 10 is a flowchart of a method of manufacturing an apparatus,according to one embodiment; and

FIG. 11 is a flowchart of a method of constructing an integratedcircuit, according to one embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENT DISCLOSURE

Hereinafter, embodiments of the present disclosure are described indetail with reference to the accompanying drawings. It should be notedthat the same elements will be designated by the same reference numeralsalthough they are shown in different drawings. In the followingdescription, specific details such as detailed configurations andcomponents are merely provided to assist with the overall understandingof the embodiments of the present disclosure. Therefore, it should beapparent to those skilled in the art that various changes andmodifications of the embodiments described herein may be made withoutdeparting from the scope of the present disclosure. In addition,descriptions of well-known functions and constructions are omitted forclarity and conciseness. The terms described below are terms defined inconsideration of the functions in the present disclosure, and may bedifferent according to users, intentions of the users, or customs.Therefore, the definitions of the terms should be determined based onthe contents throughout this specification.

The present disclosure may have various modifications and variousembodiments, among which embodiments are described below in detail withreference to the accompanying drawings. However, it should be understoodthat the present disclosure is not limited to the embodiments, butincludes all modifications, equivalents, and alternatives within thescope of the present disclosure.

Although the terms including an ordinal number such as first, second,etc. may be used for describing various elements, the structuralelements are not restricted by the terms. The terms are only used todistinguish one element from another element. For example, withoutdeparting from the scope of the present disclosure, a first structuralelement may be referred to as a second structural element. Similarly,the second structural element may also be referred to as the firststructural element. As used herein, the term “and/or” includes any andall combinations of one or more associated items.

The terms used herein are merely used to describe various embodiments ofthe present disclosure but are not intended to limit the presentdisclosure. Singular forms are intended to include plural forms unlessthe context clearly indicates otherwise. In the present disclosure, itshould be understood that the terms “include” or “have” indicateexistence of a feature, a number, a step, an operation, a structuralelement, parts, or a combination thereof, and do not exclude theexistence or probability of the addition of one or more other features,numerals, steps, operations, structural elements, parts, or combinationsthereof.

Unless defined differently, all terms used herein have the same meaningsas those understood by a person skilled in the art to which the presentdisclosure belongs. Terms such as those defined in a generally useddictionary are to be interpreted to have the same meanings as thecontextual meanings in the relevant field of art, and are not to beinterpreted to have ideal or excessively formal meanings unless clearlydefined in the present disclosure.

The present disclosure relates to GNSS receivers and, in particular, toa system and a method for improving sensitivity, speed, and quality ofmeasurements available.

According to one embodiment, the present system combines acquisitionhypotheses and track correlation hypotheses to improve the effectivesignal-to-noise ratio (SNR) going into receiver signal metrics. Thepresent system and method puts multiple hypotheses from an acquisitionphase into a track phase with the acquisition hypotheses being combinedwith accumulated track NCSs to improve the effective SNR available forreceiver signal metrics available in track. The receiver signal metricsinclude, but are not limited to, signal energy check, lock detection,continuous wave (CW) detection, cross correlation detection, multipathdetection, frequency side lobe detection, range measurement, and rangerate measurement.

FIG. 1 is a GNSS receiver 100, according to one embodiment. Although thepresent system and method is described with respect to a GlobalPositioning System (GPS), the present system and method are not limitedthereto but may be applied to all types of GNSS systems (e.g. GPS,Glonass, Galileo, Beidou, and augmentation systems).

Referring to FIG. 1, the GNSS receiver 100 includes an antenna 101, aradio frequency/intermediate frequency (RF/IF) device 103, an array ofanalog-to-digital converters 105, a carrier mixer and filter 107, asample storage memory 109, a carrier mixer 111, a local carriergenerator 113, an array of matched filter/correlators 115, a local codeclock generator 117, a course (or clear)/acquisition (C/A) codegenerator 119, a Fast Fourier Transform (FFT) device 121, a square-rootdevice 123, a non-coherent summation (NCS) hypothesis summation andstorage memory 125, a peak sorter 127, and a microprocessor 129.

Typical hypothesis search parameters for weak signal acquisition andtrack include a time uncertainty range of approximately ±10 μsecs; afrequency uncertainty range of approximately ±160 Hz; a typical codehypothesis of ½ (or ¼) chip correlation separation and, thereforeapproximately 42 code hypotheses; a typical frequency hypothesis of 15Hz and, therefore, approximately 22 carrier frequency hypotheses; atotal number of hypothesis created of the number of code hypothesestimes the number of carrier frequency hypotheses (e.g. 42×22=924); atypical coherent integration time of 20 msecs; a typical maximum NCStime of 5-8 seconds (where 8 seconds provides better performance); and atypical separate acquisition and track with 5 seconds NCS time providesa sensitivity of approximately −156 dBm, or 14 dB-Hz assuming a receiversensitivity (SEN) of 4 dB.

A standards-based mobile station assisted (MSA) test requires a GNSSreceiver to perform measurements on satellites and output thosemeasurements within 20 seconds. The 20 seconds include acquisition,track, and measurement formation of weak signals (as well as otherreceiver functions including strong and medium signal strengthsearches).

FIG. 2 is an illustration of an acquisition search space, according toone embodiment. The acquisition and search space may be in a form of N×Mtotal hypotheses, where N and M are integers. The present system selectsa top K values from the N×M acquisition hypotheses to potentially put ina track phase. The K values include, but are not limited to, 2, 4, 8,and 16.

Referring to FIG. 2, the present system provides peak selection toremove duplicate or near duplicate hypotheses. A near duplicatehypothesis is one that is close in terms of code phase and carrierfrequency (e.g. within ½ chip in code phase and within 10 Hz in carrierfrequency). The present system provides peak selection to select a setof J hypotheses from the K hypotheses. The set of J hypotheses has peaksp₁, p₂, . . . , p_(N), where p₁ is a maximum peak. In a finetime/frequency aiding case there is a high probability that the peaksort contains duplicates. The present system provides peak selection toremove duplicates where if any two peaks are within L Hz (e.g. 10 Hz)and R chips (e.g. ½ chip) then the present system only selects the peakwith the highest p value for verification, where L and R are realnumbers. As such, the set of J hypotheses with peaks sorted may beincreased (e.g. from 4 to 8) to anticipate that duplicates and nearduplicates may be rejected. The J values include, but are not limitedto, 1, 2, 4, and 8 (J<K). Each selected hypothesis includes adjacentcode phase and carrier frequency bins. Adjacent bins are required tofurther compute track function and other receiver metrics. The binvalues shown define the boundary of the two dimensional search space, Ncode phase bins times M carrier frequency bins. This is the entiresearch space in that if there is signal energy it must be present withinthis grid, this is because the mechanism by which the aiding isgenerated guarantees this. FIG. 3 described below is a subset of thesearch space shown in FIG. 2. Peak energy from FIG. 2 was found atlocation P_(M,N) in FIG. 3. Note that because there is always noisepresent there is always uncertainty as to where the real peak is. Thesearch bins in FIG. 2 are integer bins and in FIG. 3 interpolation maybe used to provide a better estimate, a fractional bin estimate.

FIG. 3 is an illustration of an acquisition peak (P_(m,n)) and adjacentcorrelators in code phase and carrier frequency domains, according toone embodiment. The adjacent correlators may be used to interpolate incorrelation delay and carrier frequency domains to estimate the peakcode phase and carrier frequency from the acquisition correlations.Interpolated correlations may be identified as P*_(m,n).

Referring to FIG. 3, the P_(m,n) and/or P*_(m,n) values are stored atthe end of the acquisition process and thereafter used in combinationwith further track mode NCS to improve the SNR metric. NCSs createdduring track may be labelled T_(m,n). Correlations developed duringacquisition and track may be stored separately and summed when requiredto enhance metrics such as lock detect and CW detect. The metrics aretypically a function of the NCS correlations, but may also be a functionof coherent values as in metric=f(I, Q) where I and Q are 20 mseccoherent summations.

For example, the present system may set up track channels for 2 toppeaks found during acquisition. The present system closes the trackingloops (code+automatic frequency calibration (AFC)) on the 2 trackchannels. The correlators out of acquisition are stored as F±4, where Fis a frequency, nominally 9 correlators in frequency domain, pluscorrelations in correlation time domain (¼ chip spaced E Hz and L Hz,where E and L are real numbers). In the two track channels thecorrelators F±4 are replicated (nominally 9 correlations at centerfrequency), including being separated by 15.625 Hz. The frequency domaincorrelators will be used via interpolation to provide a delta rangemeasurement (similarly the correlation delay domain correlators are usedvia interpolation to provide a range measurement). The acquisitioncorrelation hypothesis is accumulated with the equivalent trackcorrelation hypothesis and used together before executing an impairmentmetric. For example, F_(k total)=F_(k acq)+F_(k track). An impairmentmetric is an indicator or measurement of something that impairs anability to receive a clean signal. For example, a large CW interfererwill make it difficult to form GNSS measurements without a large error(the large error leading to bad position fixes). There are a number ofevents that can impair. Interference is one, multipath is another. Ingeneral, a receiver may take evasive or corrective action if there issome indication, for example, to use the measurement in the navigationsolution if it is indicated as a CW or has too much multipath, or use itin the navigation solution with a corrected weighting.

FIG. 4 is a chart of a waveform of acquisition/track frequency bins,according to one embodiment.

Referring to FIG. 4, the present system combines acquisition and trackhypotheses to improve lock detection. A lock detector determines thepresence or absence of a satellite signal. A power detector based onin-phase (I) and quadrature (Q) coherent correlations is used. Lockdetection is formed by observing an estimated punctual correlationsignal. A basic lock detect observation equation is given in Equation(1) as follows:

L _(Detect)=Σ_(1 . . . K)√(I _(k) ² +Q _(k) ²)  (1)

where I_(k) and Q_(k) are coherent correlations at time k. Thenon-coherent combination of I_(k) and Q_(k) is summed across K periods,where K is an integer.

A typical lock detect function is if(T_(m,n)>nest×threshold) thenlock_detect=true, else lock_detect=false, where n_(est) is a receiver'snoise estimate commonly implemented in GNSS receivers.

According to one embodiment, the present system combines acquisition andtrack correlators to form I and Q on-frequency correlators, and thenforms a lock detect. The present lock detect metric is updated asif([P_(m,n)+T_(m,n)]>nest×threshold) then lock_detect=true, elselock_detect=false. However, the threshold may need to be adjusted fromthe if(P_(m,n)>nest×threshold) case.

According to one embodiment, the present system combines acquisition andtrack hypotheses to improve CW detect. A CW detector determines whethera CW signal is present or not. A typical CW detect function is given inEquation (2) as follows:

if( C_(punctual) < (CW_(threshold) * C_(offset)) ) (2) CW_present_flag =true; else CW_present_flag = false;where CW_present_flag=true indicates that the measurement is not sent tothe navigation solution. C_(punctual) is the NCS summation across periodK (K is from a set {0.16, 0.32, 0.64, 1.28, 2.56, 5.12} seconds in 0.16second power of two mode, the other mode presented checks for CWdetection every 0.16 seconds). The coherent integration period is 20msecs. C_(punctual) is the punctual code phase in the on-frequency bin.

C_(offset) is the mean of M offset correlations, in the on-frequencybin.

FIG. 5 is an illustration of an on-frequency bin correlator usage mode,according to one embodiment.

Referring to FIG. 5, each C_(m) is an NCS summation across period K,coherent integration period 20 msecs. C₁ is an “earliest” correlator ina 16 tap window. C₁, C₂, . . . , and C_(M) are ¼ chip spaced. M is equalto 6, and is the recommended number of correlators in the computation ofC_(offset).

According to one embodiment, the present system combines acquisition andtrack correlators such that C_(punctual) and C_(m) are based on combinedacquisition and track correlators, where C_(offset) is equal to a meanof C₁, C₂, . . . , and C_(M).

According to one embodiment, the present system combines acquisition andtrack hypotheses to improve frequency side lobe detect. A frequency sidelobe detector determines a difference between a lock to a main frequencylobe and a frequency side lobe. There is only one main lobe but thereare many side lobe frequency lock possibilities. The frequency side lobedetector uses NCS sums in 5 available frequency bins that are labeledFFT1, FFT2, . . . , FFT5. The frequency bins represent frequency offsetversions of the punctual code phase tracking correlators. FFT3 is theon-frequency bin when a satellite is being tracked. Bins FFT2 and FFT4are used in the AFC tracking loop.

A typical side lobe detect function is given in Equation (3) as follows:

if( abs(FFT1 − FFT5) / FFT3 > threshold ) (3) side_lobe_lock_flag =true; else side_lobe_lock_flag = false;where FFT1, FFT3, and FFT5 are NCS summations across period K seconds(e.g. coherent integration period of 20 msecs).

According to one embodiment, the present system combines acquisition andtrack correlation hypotheses such that FFT1, FFT3, and FFT5 are NCSsummations based on the combined acquisition and track correlators.

According to one embodiment, the present system combines acquisition andtrack correlation hypotheses for multipath mitigation.

According to one embodiment, the present system combines correlationhypotheses developed during an acquisition phase and track phase toimprove range and range rate measurements. TCXO and Doppler frequencyrate terms may be small. A TCXO frequency rate is measured by sampling aCP's measurement of it often (e.g. 1 Hz rate). Doppler frequency rate isexpected to be smaller (max 1 Hz/sec vs. max 4 Hz/sec). LTE sends theDoppler rate as an aiding message. Limiting the unknown frequency rateallows the signals to remain relatively stationary during acquisitionand track phases. NCS correlations are accumulated in code delay andcarrier frequency domains across acquisition and track (e.g. 8+8=16seconds). Interpolation is done across code phase and carrier frequencydomains. For example, total NCS equals 7 (code) times 7 (carrier).According to one embodiment, the present system does not close trackingloops before a first measurement, and may close tracking loops at anytime after the first measurement (i.e., early due to highercarrier-to-noise-density ratio (CNO) present).

FIG. 6 is an illustration of NCS propagation, according to oneembodiment.

Referring to FIG. 6, NCS_(output)=NCS_(acq)×(4.5RR_(acq))+Σ_(k=1 . . . 7)NCS_(k)×(1 RR_(k)), andrange_(measurement)=Peak_(interpolation)(NCS_(output)), where RR isrange rate estimate (either from network aiding or network aiding plusGNSS AFC loops). RR_(acq) is a best estimate of range rate across 4.5seconds between reference time of acquisition and reference time ofNCS₁. RR_(k) is best estimate of range rate across 1 second betweenreference time of last track second (NCS_(k-1)) and reference time ofcurrent track second (NCS_(k)).

NCS propagation allows the present system to combine all NCS summationsacross acquisition and track to improve measurement quality i.e., rangemeasurement and range rate measurement.

FIG. 7 is a flowchart of a method of NCS propagation, according to oneembodiment.

Referring to FIG. 7, the time sequence illustrated is relevant to theweakest signals, although at any time during acquisition and track, ameasurement may be formed if a sufficiently strong signal is present.The weakest signals are typically in the range of −160 dBm to −156 dBm(10 to 14 dB-Hz), but may go significantly lower in the future withextended coherent integration (on pilot signals) and better medium termTCXO stabilities. Different satellites may be acquired and tracked atdifferent times by a receiver, with different CNOs in each case.

At 701, NSC acquisition (NCS_(acq)) correlators are read.

At 703, an acquisition rate range (RR_(acq)) is computed.

At 705, NCS_(acq) is propagated from time A to time B, where A and B arereal numbers.

At 707, the propagated NCS_(acq) is added to a latest NCS.

At 709, it is determined if a track of 8 seconds is ended. If not, themethod returns to 707. Otherwise, the method proceeds to 711.

At 711, NCS is interpolated to find a peak.

At 713, a measurement of a range (RANGE_(measurement)) is output.

FIG. 8 is an illustration of an acquisition phase and a track phasetimeline, according to one embodiment.

Referring to FIG. 8, A seconds and B seconds may be the same ordifferent.

FIG. 9 is a flowchart of a method of acquisition and track processes,according to one embodiment.

The following illustrates metric input SNR computations for variousscenarios. In one scenario, −160 dBm=10 dB-Hz (4 dB receiver SEN).

Best SNR available at −156 dBm with track only 20 msec coherent and 5seconds NCS integration: SNR=14dB-Hz+10*log₁₀(0.02)+5*log₁₀(50×5)=14-17+12=9 dB.

Combining acquisition and track with 5 secs NCS at −156 dBm: SNR=14dB-Hz+10*log₁₀(0.02)+5*log₁₀(2×50×5)=14-17+13.5=10.5 dB.

Combining acquisition and track with 8 secs NCS at −156 dBm: SNR=14dB-Hz+10*log₁₀(0.02)+5*log₁₀(2×50×8)=14-17+14.5=11.5 dB.

Combining acquisition and track with 8 secs NCS at −158 dBm: SNR=12dB-Hz+10*log₁₀(0.02)+5*log₁₀(2×50×8)=12-17+14.5=9.5 dB, or SNR=9 dB at−158.5 dBm.

It is observed that −158 dBm should be possible for fine time/frequencyadding MSA.

According to one embodiment, the present system and method improves GNSSsensitivity via combining of acquisition and track correlationhypotheses, including selecting a subset of acquisition hypotheses froma set of acquisition hypotheses during an acquisition phase. During asubsequent tracking phase, the present system provides tracking mode NCSusing the subset of acquisition hypotheses from the acquisition phasewith track hypotheses, where the combined acquisition and track NCS areused in various signal metrics such as signal energy check, lockdetection, CW detection, cross correlation detection, multipathdetection, frequency side lob detection, range measurement, and rangerate measurement.

Referring to FIG. 9, high sensitivity acquisition is conducted at 901. Kvalues of N peaks and code phase and frequency hypotheses are stored,where K and N are integers.

At 903, J peaks of the high sensitivity acquisition are selected, whereJ is an integer.

At 905, the J selected peaks are put into track.

At 907, acquisition and track NCS summations in metrics (e.g. lockdetect and other metrics) are combined, resulting in more SNR availablefor metrics.

At 909, if the metrics are sufficient (e.g., good, the metrics do notindicate that the measurement should be abandoned), measurements areformed. A good range measurement is one that has low error as observedvia the positioning and high level application. For example, in urbancanyon navigation, 10 meters may be an acceptable position fix error.This indicates that the individual range measurements used in theposition computation may have to be accurate on average to <3 meters. Agood measurement is one that meets this specification. A rangemeasurement derived from CW track may be off by many kilometers soidentifying the track as CW (and the improved SNR helps) is beneficial.

FIG. 10 is a flowchart of a method of manufacturing an apparatus,according to one embodiment.

Referring to FIG. 10, an apparatus is formed on a wafer or a packagewith at least one other apparatus, where the apparatus includes aprocessor configured to conduct high sensitivity acquisition, select Jpeaks of the high sensitivity acquisition, where J is an integer,combine acquisition and track NCSs in metrics, and form measurements ifthe metrics are sufficient (e.g., the metrics do not indicate that themeasurement should be abandoned), at 1001.

At 1003, the apparatus is tested. Testing the apparatus may includetesting the apparatus using one or more electrical to opticalconverters, one or more optical splitters that split an optical signalinto two or more optical signals, and one or more optical to electricalconverters.

FIG. 11 is a flowchart of a method of constructing an integratedcircuit, according to one embodiment.

Referring to FIG. 11, initial layout data is constructed in 1101. Forexample, a mask layout is generated for a set of features for a layer ofthe integrated circuit, wherein the mask layout includes standard celllibrary macros for one or more circuit features that include anapparatus that includes a processor configured to conduct highsensitivity acquisition, select J peaks of the high sensitivityacquisition, where J is an integer, combine acquisition and track NCSsin metrics, and form measurements if the metrics are sufficient (e.g.,the metrics do not indicate that the measurement should be abandoned).Relative positions of the macros may be disregarded for compliance tolayout design rules during the generation of the mask layout.

At 1103, a design rule check is performed. For example, the method maycheck the relative positions of the macros for compliance with layoutdesign rules after generating the mask layout.

At 1105, the layout is adjusted. For example, the method, upon detectionof noncompliance with the layout design rules by any of the macros, maymodify the mask layout by modifying each of the noncompliant macros tocomply with the layout design rules.

At 1107, new layout data is generated. For example, the method maygenerate a mask according to the modified mask layout with the set offeatures for the layer of the integrated circuit. Then, the integratedcircuit layer according to the mask may be manufactured.

Although certain embodiments of the present disclosure have beendescribed in the detailed description of the present disclosure, thepresent disclosure may be modified in various forms without departingfrom the scope of the present disclosure. Thus, the scope of the presentdisclosure shall not be determined merely based on the describedembodiments, but rather determined based on the accompanying claims andequivalents thereto.

What is claimed is:
 1. An apparatus, comprising: a memory; and aprocessor configured to: conduct acquisition of K values with N peaks,where K and N are integers; store the K values in the memory; select Jof the N peaks and include the J peaks in track, where J is an integerless than or equal to N; combine acquisition and track non-coherentsummations (NCSs) of coherent correlations in a metric; and form ameasurement unless the metric indicates that the measurement should beabandoned.
 2. The apparatus of claim 1, wherein the apparatus is one ofa global navigation satellite system (GNSS) including a globalpositioning system (GPS), Glonass, Galileo, Beidou, and an augmentationsystem.
 3. The apparatus of claim 1, wherein the N peaks are highestenergy peaks.
 4. The apparatus of claim 1, wherein the metric is one ofa signal energy check, lock detection, continuous wave (CW) detection,cross correlation detection, multipath detection, frequency side lobedetection, range measurement, and range rate measurement.
 5. Theapparatus of claim 2, wherein the GNSS comprises: an antenna; a radiofrequency/intermediate frequency (RF/IF) device connected to theantenna; an analog-to-digital converter (ADC) connected to the RF/IFdevice, including an input for receiving a frequency signal, and anoutput bus; a carrier mixer and filter connected to the ADC; a samplestorage memory connected to the carrier mixer and filter; a localcarrier generator; a carrier mixer connected to the sample storagememory and the local carrier generator; a local code clock generator,including an input for receiving a code phase signal; acourse/acquisition (C/A) code generator connected to the local codeclock generator, including an input for receiving a code select signal,and an output bus; an array of matched filter/correlators connected tothe carrier mixer and the C/A code generator; a Fast Fourier Transform(FFT) connected to the array of matched filter/correlators; a squareroot device connected to the FFT; an NCS hypothesis summation andstorage memory connected to the square root device; a peak sorterconnected to the NCS hypothesis summation and storage memory; and amicroprocessor connected to the peak sorter.
 6. The apparatus of claim1, wherein the J peaks do not include duplicates or near duplicates. 7.The apparatus of claim 6, wherein the near duplicate is within ½ chip incode phase and within 10 Hz in carrier frequency.
 8. The apparatus ofclaim 1, wherein each J peak includes adjacent correlators.
 9. Theapparatus of claim 8, wherein the processor is further configured to usethe adjacent correlators to estimate peak code phase and carrierfrequency from acquisition correlations.
 10. A method, comprising:conducting, by a processor, acquisition of K values with N peaks, whereK and N are integers; storing, in a memory, the K values; selecting J ofthe N peaks and including the J peaks in track, where J is an integerless than or equal to N; combining acquisition and track non-coherentsummations (NCSs) of coherent correlations in a metric; and forming ameasurement unless the metric indicates that the measurement should beabandoned.
 11. The method of claim 10, wherein the N peaks are highestenergy peaks.
 12. The method of claim 10, wherein the metric is one of asignal energy check, lock detection, continuous wave (CW) detection,cross correlation detection, multipath detection, frequency side lobedetection, range measurement, and range rate measurement.
 13. The methodof claim 10, wherein the J peaks do not include duplicates or nearduplicates.
 14. The method of claim 13, wherein the near duplicate iswithin ½ chip in code phase and within 10 Hz in carrier frequency. 15.The method of claim 10, wherein each J peak includes adjacentcorrelators.
 16. The method of claim 15, wherein the adjacentcorrelators are used to estimate peak code phase and carrier frequencyfrom acquisition correlations.
 17. A method of manufacturing anapparatus, comprising: forming the apparatus on a wafer or a packagewith at least one other apparatus, wherein the apparatus comprises amemory and a processor configured to conduct acquisition of K valueswith N peaks, where K and N are integers, store the K values in thememory, select J of the N peaks and include the J peaks in track, whereJ is an integer less than or equal to N, combine acquisition and tracknon-coherent summations (NCSs) of coherent correlations in a metric; andform a measurement unless the metric indicates that the measurementshould be abandoned; and testing the apparatus, wherein testing theapparatus comprises testing the apparatus using one or more electricalto optical converters, one or more optical splitters that split anoptical signal into two or more optical signals, and one or more opticalto electrical converters.
 18. The method of claim 17, wherein the metricis one of a signal energy check, lock detection, continuous wave (CW)detection, cross correlation detection, multipath detection, frequencyside lobe detection, range measurement, and range rate measurement. 19.A method of constructing an integrated circuit, comprising: generating amask layout for a set of features for a layer of the integrated circuit,wherein the mask layout includes standard cell library macros for one ormore circuit features that include an apparatus comprising a memory anda processor configured to conduct acquisition of K values with N peaks,where K and N are integers, store the K values in the memory, select Jof the N peaks and include the J peaks in track, where J is an integerless than or equal to N, combine acquisition and track non-coherentsummations (NCSs) of coherent correlations in a metric; and form ameasurement unless the metric indicates that the measurement should beabandoned; disregarding relative positions of the macros for complianceto layout design rules during the generation of the mask layout;checking the relative positions of the macros for compliance to layoutdesign rules after generating the mask layout; upon detection ofnoncompliance with the layout design rules by any of the macros,modifying the mask layout by modifying each of the noncompliant macrosto comply with the layout design rules; generating a mask according tothe modified mask layout with the set of features for the layer of theintegrated circuit; and manufacturing the integrated circuit layeraccording to the mask.
 20. The method of claim 19, wherein the metric isone of a signal energy check, lock detection, continuous wave (CW)detection, cross correlation detection, multipath detection, frequencyside lobe detection, range measurement, and range rate measurement.